Project Summary There is an unmet need to develop novel therapeutic targets and biomarkers for Alzheimer's disease (AD) and related disorders. During the first phase of consortium, we have added the unique dimension of discovery proteomics to the Accelerating Medicines Partnership (AMP)-AD. We successfully established a high throughput proteomics pipeline and quantified 2-3000 proteins by mass spectrometry (MS) in >1800 postmortem human brains for all AMP-AD teams. Using systems biology tools, we identified highly conserved AD proteomic networks that complement and extend transcriptomic networks, highlighting a set of protein co-expression modules strongly associated with diagnosis, cognition, and neuropathology. Experimental validation of several novel protein targets in these modules confirmed links to neurodegeneration in model systems and in human brain pathology. The overall goal of this renewal application is to fill several key gaps in AMP-AD, which are to enrich and validate the AD brain co-expression network (with coverage of >11,000 proteins, >30,000 phosphosites, and interacting proteins), and better define optimal novel targets for the entire consortium. Using new MS technologies and proven cross-species experimental strategies, we will provide high confidence of module membership necessary to guide therapeutic and biomarker applications. We also will translate these targets into actionable biomarkers to monitor these modules and the respective pathophysiologies in living subjects with the following aims: 1) Integrate proteomics, phosphoproteomics and protein-protein interactions to extend AD networks and define key signaling and pathophysiological pathways linked to AMP-AD targets; 2) Validate predicted network structure for the most promising AMP-AD targets in experimental model systems; and 3) Translate the list of nominated AMP-AD targets including key trait-associated modules and hub proteins into novel CSF biomarkers for AD. The results will amplify the impact of the AMP-AD with rapid and full data sharing and establish an innovative pipeline for discovery and validation of brain proteomics targets and companion CSF biomarkers that serve as robust and reproducible indicators of AD, including the dysregulated processes that occur in brain.